1. Field of the Invention
Gasket material, more specifically, a gasket material comprising a resilient, pliable body having a skeletal mesh member embedded therein.
2. Background Information
A gasket is a sealing member for use between two mating surfaces to help prevent the movement of fluid or gas between the mating surfaces. Gaskets are often used on vehicles such as aircraft to prevent moisture from corroding the sealed off areas and the mating surfaces. For example, on the outside skin of an aircraft antenna are often mounted to assist in communications between the aircraft and a remote location. Such antennas often consist of a tabular mounting plate having an inner and outer surface, the inner surface mating to the outer skin of the aircraft and having an electrical connector projecting from the inner surface. The electrical connector is intended to fit partially into the interior of the aircraft through a small opening in the aircraft skin designed for such purpose. The electrical connector element will connect to the appropriate electrical circuit in the aircraft. On the outer surface of the mounting plate, and often incorporated with the mounting plate, is the antenna transceiving member for transmitting and/or receiving radio frequencies.
Traditionally, the antenna is removably mounted to the aircraft through typical threaded fasteners. Holes in the tabular mounting plate of the antenna support the threaded fasteners which pass into the aircraft""s skin, typically threading into blind nuts mounted against the inside surface of the aircraft""s skin.
Gaskets typically are provided for covering a portion of the xe2x80x9cfootprintxe2x80x9d of the antenna against the outer surface of the aircraft. When the fasteners are tightened down, they compress the gasket typically with some defamation, between the aircraft""s skin and the inner surface or face of the antenna mounting plate. This is done in an effort to prevent moisture from penetrating the gasket barrier.
However, prior art gaskets have a number of shortcomings which applicants novel gasket material overcomes. These shortcomings include allowing moisture to penetrate the area between the antenna and the aircraft""s skin. Often, for example, a site of corrosion is the junction between the antenna inner surface and the electrical connective elements of the antenna. Moisture has been found to xe2x80x9cpoolxe2x80x9d in this area, accelerating corrosion. Further shortcomings of the prior art gaskets include their moisture content or moisture absorption ability, which moisture may encourage the formation of corrosion, when the gasket is under pressure between the mating surfaces and, especially, where such gasket includes a metallic element. Further shortcomings of the prior art gaskets include their xe2x80x9cnon-selective retentivity.xe2x80x9d This means that after the gasket has been installed and in use for a period of time, that upon an attempt to separate the antenna from the aircraft""s skin, some portions of the gasket will non-selectively stick to portions of the aircraft""s skin and other portions of the gasket will stick to the antenna (see FIG. 1A.). The result, often, is the destruction of the gasket.
Applicants have invented a gasket with a novel combination of properties and qualities that effectively prevent moisture from passing the sealed area while maintaining selective retentivity. This allows the effective separation between the mating surfaces upon removal of the antenna.
Flexibility, resiliency, compressibility and pliability are other favorable properties which help affect a good seal between the mating surfaces.
All of these beneficial properties should have a useful life that is reasonable in view of operating conditions and aircraft maintenance schedules. The gasket should be inert, that is non-reactive with the work pieces (typically aluminum) as well as non-reactive to water, including salt water.
Not surprisingly, it has proven to be a challenge to develop a gasket with these properties that will survive repeated heat and pressure cycling (as the aircraft climbs and descends), structural flexing, and vibration while protecting the aircraft components and having a useful life.
While some of the prior art gaskets have provided some of the favorable properties set forth above, none have provided all of these properties in an aircraft gasket with a useful life. Such typical useful life would be a minimum of greater than one year under proper torque specifications.
Applicants, however, provide for all of the above properties in an aircraft gasket and gasket tape and a novel method of manufacturing the aircraft gasket and gasket tape. Gasket tape is gasket material that is rolled into tape rather than precut to the pattern of the mating surfaces. Applicants further provide for a method of using the preformed gasket with a liquid setable gel too, in some cases, help insure a waterproof seal.
Applicants have also found a novel method of preparing a gasket material.
Applicants provide a gasket with the following beneficial properties, heretofore unavailable in a preformed gasket or a gasket tape: elasticity (with memory), low water absorption, low water content, leak free (especially of silicon oil), dessication resistant, compressibility and surface tackiness (including selective retentivity).
The elasticity and pliability helps make an effective seal between the two mating surface as compression against such elasticity helps seal over mating surface irregularities and structural flexing or vibration of the two surfaces. The maintenance of this elasticity property is important since the surfaces undergo thermal expansion and contraction during repeated altitude and temperature changes which causes relative movement (flexing) between the mating surfaces.
Low water absorption and low water content is also a beneficial quality as it is typically water or moisture that the gasket is meant to keep out.
Nor should a gasket material itself be the source of oil, as such oil can mar the finish of the aircraft surface. This oil leaching has been a problem with prior art gaskets including those silicon-based gaskets.
An additional beneficial property of an effective gasket includes a resistence to drying out. Drying out of a gasket brings the problem of shrinkage and break-up, which destroys the integrity of the gasket/mating surface.
Tackiness has been found beneficial since there is also vibration and flexing of the mating surfaces. Tackiness and resiliency provide a better seal should there be a slight separation between the mating surfaces.
Applicant""s novel gasket consists of two parts. The first part comprises a skeletal memberxe2x80x94typically an open-weave mesh member and, more typically, an open-woven mesh made of a metallic material or a non-metallic fabric such as fiberglass.
The second part of applicant""s novel gasket is a flexible resilient body member typically formed around and through the skeletal member so that the skeletal member is substantially encapsulated within the resilient body member and gives some structure and form to the gasket.
The gasket and gasket tape are usually tabular in shape and the skeletal member and resilient body share a tabular shape and plane. However, when viewed in cross-section, Applicants skeletal member is not centered between the two opposed tabular surfaces of the gasket (or gasket tape), but instead is closer to one surface than the other. It is believed that this property provides selective retentivity to the material.
The resilient body is typically comprised of a semi-solid gelatin polyurethane, typically between 40 and 150 (10xe2x88x921 mm) cone penetration and having a surface tackiness of between about 2 to 7 inch pounds and which tackiness allows some adhesion to a metal mating surface, but will release easily and leave no residue upon release. The resilient body will not undergo dessication, does not leak oil, but retains memory and does not absorb more than about one percent by weight water. Other resilient, pliable bodies may be used, such as silicon or polyolefinic block copolymers or other materials with similar cone penetration and tackiness.